Californium is a radioactive chemical element with the symbol Cf and atomic number 98. The element was first synthesized in 1950 at Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory), by bombarding curium with alpha particles (helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all elements that have been produced in amounts large enough to see with the naked eye (after einsteinium). The element was named after the university and the U.S. state of California.

Two crystalline forms exist for californium at normal pressure: one above and one below 900 C (1,650 F). A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. Californium compounds are dominated by the +3 oxidation state. The most stable of californium's twenty known isotopes is californium-251, with a half-life of 898 years. This short half-life means the element is not found in significant quantities in the Earth's crust. 252Cf, with a half-life of about 2.645 years, is the most common isotope used and is produced at Oak Ridge National Laboratory in the United States and Research Institute of Atomic Reactors in Russia.

Californium is one of the few transuranium elements with practical applications. Most of these applications exploit the property of certain isotopes of californium to emit neutrons. For example, californium can be used to help start up nuclear reactors, and it is employed as a source of neutrons when studying materials using neutron diffraction and neutron spectroscopy. Californium can also be used in nuclear synthesis of higher mass elements; oganesson (element 118) was synthesized by bombarding californium-249 atoms with calcium-48 ions. Users of californium must take into account radiological concerns and the element's ability to disrupt the formation of red blood cells by bioaccumulating in skeletal tissue.

The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant university and the first campus of the University of California system. Its fourteen colleges and schools offer over 350 degree programs and enroll some 31,000 undergraduate and 12,000 graduate students. Berkeley is ranked among the world's top universities.A founding member of the Association of American Universities, Berkeley hosts many leading research institutes, including the Mathematical Sciences Research Institute and the Space Sciences Laboratory. It founded and maintains close relationships with three national laboratories at Berkeley, Livermore and Los Alamos, and has played a prominent role in many scientific advances, from the Manhattan Project and the discovery of 16 chemical elements to breakthroughs in computer science and genomics. Berkeley is also known for political activism and the Free Speech Movement of the 1960s.Berkeley's athletic teams, which compete as the California Golden Bears primarily in the Pac-12 Conference, have won 107 national championships, and its students and alumni have won 223 Olympic medals (including 121 gold medals).Berkeley alumni and faculty count among their ranks 55 Nobel laureates, 25 Turing Award winners, 14 Fields Medalists, 30 Wolf Prize winners, 108 MacArthur "Genius Grant" recipients, 30 Pulitzer Prize winners, and 19 Academy Award winners. The university has produced seven heads of state or government; six chief justices, including Chief Justice of the United States Earl Warren; 22 cabinet-level officials; 11 governors; and 25 living billionaires. It is also a leading producer of Fulbright Scholars, MacArthur Fellows, and Marshall Scholars. Berkeley alumni, widely recognized for their entrepreneurship, have founded numerous notable companies, including Apple, Tesla, Intel, eBay, SoftBank, AIG, and Morgan Stanley.